Specifications Relating to Non-automatic Weighing Devices (1998) (SI/98-81)

Acceptance Limits of Error

9 The acceptance limits of error applicable for each class of non-automatic weighing device are one-half the in-service limits of error set out in section 8 for that device for a specified load.

Modules

10 Where a module, such as an indicating element, or a weighing and load-receiving element, is tested separately for approval pursuant to section 3 of the Weights and Measures Act,

• (a) in the case of a module that is the only part of a weighing device that is subject to measurement errors due to disturbances or influence factors, the acceptance limits of error are the limits of error set out in these Specifications for that device for a specified load; and

• (b) in the case of all other modules, the acceptance limits of error are 0.7 times the limits of error set out in these Specifications for the weighing device for a specified load.

Differences Between Results

11 Regardless of the difference between the results permitted by these Specifications, no weighing result shall have an error that exceeds the applicable limits of error for the given load, with the exception of results obtained during disturbance tests.

Repeatability

12 The difference between the results of several weighings of the same load placed in approximately the same location on a weighing and load-receiving element shall not exceed the absolute value of the applicable in-service limits of error for that load.

Eccentric Loading

13 The difference between the results for different positions of a load placed on a weighing and load-receiving element shall not exceed the absolute value of the applicable in-service limits of error for that load.

Load Discrimination and Sensitivity

14 With respect to non-automatic indicating devices, the addition or removal of a load equal to the applicable in-service limits of error for the load placed on the weighing and load-receiving element, but not exceeding two verification scale intervals, shall cause

• (a) in the case of a weigh-beam or beam-over-pan scale that is without a supplementary indicating element and

  • (i) is equipped with a trig loop, a movement in the position of the weigh-beam from the centre position to either limit of the trig loop, and

  • (ii) is not equipped with a trig loop, the position of rest of the weigh-beam or lever system to change from the horizontal position or midway between limiting stops to either limit of motion; and

• (b) in the case of a weigh-beam or beam-over-pan scale that has a supplementary indicating element that has graduations without specific values, the position of the indicator to change

  • (i) in the case of a Class or device, by at least 1 mm (0.04 in.),

  • (ii) in the case of a Class or device with a maximum capacity not exceeding 30 kg (70 lb.), by at least 2 mm (0.08 in.), and

  • (iii) in the case of a Class or device with a maximum capacity greater than 30 kg (70 lb.), or a Class device, by at least 5 mm (0.2 in.).

15 With respect to automatic indicating devices, the addition or removal of a load equivalent to 1.4 times the actual scale interval to or from the weighing and load-receiving element shall cause a change of

• (a) in the case of an analogue indicating element, at least one actual scale interval; and

• (b) in the case of a digital indicating element, two actual scale intervals.

Return-to-Zero

• 16 (1) Under stable environmental conditions, the deviation from zero as soon as the weight indication has stabilized following the removal of a load that has remained on a weighing and load-receiving element for up to 30 minutes shall not exceed

  • (a) in the case of a single range weighing device, one-half of the verification scale interval;

  • (b) in the case of a multiple range device, one-half of the verification scale interval for the range being tested; and

  • (c) in the case of a multi-interval device, one-half of the smallest verification scale interval.

• (2) In the case of a multiple range device, following the removal of a load greater than the maximum capacity of the first range, which load has remained on the weighing and load-receiving element for up to 30 minutes, and immediately after switching the device to its lowest weighing range, the indication near zero shall not vary by more than one verification scale interval of the lowest weighing range over a period of five minutes after switching the device to its lowest weighing range.

Creep

17 If a load is kept on a weighing and load-receiving element under stable environmental conditions, the difference between the weight indication obtained immediately after placing the load on the element and the weight indication observed during the following 30 minutes shall not exceed the absolute value of the applicable limits of error for that load.

Agreement of Indications and Recordings

18 The weight values that are indicated or recorded by the indicating and recording elements of a weighing device and any equipment and accessories attached to the weighing device or used in conjunction with it shall agree

• (a) exactly, in the case of digital values produced by electronic elements, equipment and accessories that have the same verification scale intervals;

• (b) within 0.25 times the verification scale interval, in the case of analogue values produced by elements, equipment and accessories that have the same verification scale intervals; and

• (c) within 0.6 times the largest verification scale interval or the verification scale interval common to the elements, equipment and accessories, in all other cases.

Computation

• 19 (1) The calculated value of the net weight shall equal the value of the gross weight minus the value of the tare weight.

• (2) Indicated or recorded monetary value shall equal the product, rounded to the nearest cent, obtained by multiplying the weight indication or registration by the price per unit.

Durability

20 A weighing device shall maintain its metrological characteristics and perform within the applicable limits of error for at least 100 000 weighings for a weighing device with a maximum capacity of not more than 1 000 kg (2 000 pounds), and for at least 300 weighings in all other cases.

Performance – Influence Factors

Off-level Effect

• 21 (1) A portable or movable weighing device, other than a device of the freely suspended type or an on-board weighing system, shall be equipped with a permanent means of indicating when it is level, unless it is capable of performing within the applicable limits of error when tilted up to three degrees or five per cent in any direction from a level position.

• (2) An on-board weighing system shall be

  • (a) capable of performing within the applicable limits of error when tilted up to three degrees or five per cent in any direction from a level position; and

  • (b) equipped with a means to blank the weight indications and prevent the transmission, printing and storage of the weight results when the registrations are no longer within the applicable limits of error.

Declared Conditions of Use

22 A weighing device shall perform within the applicable limits of error when exposed to the range of conditions specified by the manufacturer, as well as at any temperature, humidity, pressure, voltage, frequency or other influencing factors that may be encountered under normal conditions of use.

Temperature Effect on No Load Indication

23 The weight indication at or near zero shall not vary by more than

• (a) in the case of Class weighing devices, one verification scale interval for each change in temperature of 1°C;

• (b) in the case of Class weighing devices, three verification scale intervals for each change in temperature of 5°C; and

• (c) in the case of all other classes of weighing device, one verification scale interval for each change in temperature of 5°C.

Temperature

• 24 (1) A weighing device shall perform within the applicable limits of error when exposed

  • (a) where a temperature range is marked on the device, within that temperature range; and

  • (b) where no temperature range is marked on the device, at any temperature of at least -10°C and no more than 40°C.

• (2) The minimum marked temperature range on a weighing device shall be

  • (a) in the case of Class devices, 5°C;

  • (b) in the case of Class devices, 15°C; and

  • (c) in the case of Class , and devices, 30°C.

Barometric Pressure

25 The weight indication at or near zero on a weighing device shall not vary by more than one verification scale interval for a change in barometric pressure of 1 kPa in the barometric pressure range of 95 to 105 kPa.

Voltage and Frequency Variations

26 A weighing device that operates using alternating current shall, when exposed to voltage variations from -15 per cent to +10 per cent and to frequency variations of ± 2 per cent of its marked nominal values,

• (a) perform within the applicable limits of error; or

• (b) blank the weight indication and prevent the transmission, printing and storage of weight results.

27 A battery-operated weighing device, when exposed to battery voltage output less than or in excess of the nominal voltage or voltage range, shall

• (a) perform within the applicable limits of error; or

• (b) blank the weight indication and prevent the transmission, printing and storage of weight results.

Humidity

28 A weighing device shall perform within applicable limits of error when exposed to relative humidity of up to 85 per cent

• (a) where a temperature range is marked on the device, within that temperature range; and

• (b) where no temperature range is marked on the device, at any temperature of at least -10°C and no more than 40°C.

Performance – Disturbances

29 An electronic weighing device, when disturbed by interference such as the effects of electromagnetic or electrostatic fields, short time power reduction, voltage spikes, electrostatic discharges or other disturbances that may be encountered under normal conditions of use, shall

• (a) provide a weight indication or recording that does not differ from the value of the weight indication or recording that would be provided without interference by more than one verification scale interval;

• (b) blank the weight indication and prevent the transmission, printing and storage of weight results;

• (c) provide an error message and prevent the transmission, printing and storage of weight results; or

• (d) provide a weight indication that is so completely unstable that it cannot be interpreted, stored or printed as a correct measurement value.

Design, Composition and Construction

General

30 A weighing device shall be of a design, composition and construction that

• (a) under normal conditions of use, enables it to measure accurately and does not facilitate the perpetration of fraud; and

• (b) provides it with a static operating mode for inspection purposes, even if the device is designed to be used in a dynamic operating mode.

31 Weighing device features that perform metrological functions shall be designed, composed and constructed so that they

• (a) ensure accurate measurement;

• (b) do not detrimentally affect the performance of the device;

• (c) do not lead to measurement errors; and

• (d) do not facilitate the perpetration of fraud.

31.1 Neither gross values nor tare values shall be entered manually in on-board weighing systems.

32 A weighing device may perform non-metrological functions provided that those functions do not alter the metrological functions of the device.

33 Equipment and accessories attached to or used in conjunction with a weighing device shall not cause any alteration or degradation of the metrological functions of the device or facilitate the perpetration of fraud.

Indications and Recordings

• 34 (1) A weighing device shall be provided with appropriate indicating and recording elements in terms of the design, number and size of digits to permit accurate measurement.

• (2) The indications and recordings generated by a weighing device shall be clear, accurate, reliable and easy to read under normal conditions of use of the device.

Names and Symbols

35 Indications or recordings, such as weight values, tare values and monetary values, and metrologically significant annunciators shall be identified with suitably located words, names, symbols or abbreviations that will not become obliterated or illegible under normal conditions of use of the weighing device.

Scale Interval

36 Subject to section 37, the scale interval of a weighing device or any equipment and accessories attached to or used in conjunction with the device shall be equal to 1 x 10^x, 2 x 10^x, or 5 x 10^x units of mass where the power “x” is a negative or positive whole number or zero.

37 The scale interval of a weighing device with an analogue indicating element may be equal to 1/2ⁿ of a Canadian unit of mass, where “n” is a positive whole number.

• 38 (1) Subject to subsection (2), the net, gross and tare weights, whether indicated or recorded, shall have the same verification scale interval for any given load.

• (2) The scale interval of a printer may be larger than the verification scale interval of the weight classifier to which it is connected, provided that the measurement, weight classification and price calculation are established precisely and accurately.

Over-capacity

39 A weighing device shall not indicate or record a weight value in excess of

• (a) in the case of an electronic computing scale other than a postal scale or weight classifier, its maximum capacity plus 9 verification scale intervals; and

• (b) in the case of any other scale, 105 per cent of its maximum capacity.

Zero-setting and Zero-tracking Mechanisms

40 A weighing device shall have a means to set the zero indication within

• (a) ± 0.25 of the verification scale interval, in the case of a device that does not have an auxiliary indicating element; and

• (b) ± 0.5 of the actual scale interval, in the case of a device with an auxiliary indicating element.